The present invention relates to a method for attaching a tag to a tea bag, in particular for attaching a tag to a filter-bag containing tea, chamomile, and similar products, using a thread fixed to the bag at one end and to the tag at the other to form a convenient means of holding the bag itself both during and after infusion.
In the present description, reference will be made to bilobate tea bags but without thereby restricting the application of the disclosure to other kinds of tea bags.
Bilobate tea bags, which are the most common type of single-dose tea bags, are formed of a sheet of filter paper from a continuous roll, folded and sealed longitudinally to form a tube; while the tube is being formed, charges of product are deposited on the filter paper at regular intervals in a longitudinal direction; each section of tube is then folded into a W shape at the center, between two consecutive charges, so as to form the so-called lobes of the bag, each containing a charge of product. Finally, the two lobes are pressed against one another, their open ends are sealed and, at the same time, a thread connecting them to a tag is attached to them at the sealed end. The tea bag made in this way can be picked up and handled by the thread, especially after it has been placed in boiling water, since one end of the thread is fixed to the bag and the other end to a tag which can be conveniently held between the fingers.
The sealing of the bag and the attachment of the thread can be effected in different ways.
In U.S. Pat. No. 2,307,998, which discloses a type of tea bag and the method for making it, the method which envisages knots to fix the thread to the bag and to the tag is attributed to prior art; in one of the examples in the drawings and in the description, the thread is secured to the tag and to the bag by a staple with the thread knotted to it, in another example, by a knot only.
According to the above-identified patent, knotting does not lend itself to high speed production; indeed, present-day industry has adopted stapling as the fastest and most effective way of securing tags to tea bags.
The disadvantage of this method, however, especially to secure the tag thread to the bag, is that the metal which the staples are made of may contaminate the infusion creating a disagreeable taste and even health problems.
Another method of securing the thread is described in U.S. Pat. No. 4,415,597, which discloses a filter-bag made of filter paper coated with a heat sealable layer of thermoplastic material, with a tag secured by a thread held at one end between two heat sealed edges of the bag, wound around the bag and detachably heat sealed to the outside of the bag itself at several points. Hence, the bag, or at least part of it, is made of paper and thermoplastic material.
This type of material has disadvantages similar to those mentioned above, since contact between the thermoplastic material and the infusion liquid at high temperatures can lead to contamination of the brew by substances in the thermoplastic material. Another disadvantage of the bag disclosed by this patent is the cost of the thermoplastic material, which is considerably higher than ordinary filter paper.